Structure and method for connecting metal connecting ring or end socket and composite shell of large-opening engine

Abstract

A connecting structure and method for a large-opening engine metal connecting ring or end socket and a composite shell comprise connecting grooves, a cylindrical face, axial yarn and annular yarn, the multiple connecting grooves are annularly formed in the outer circle face of the connecting ring or the metal end socket, and the cylindrical face is connected to the inner side of the connecting groove in the innermost side of the connecting ring or the metal end socket. The connecting rings or the metal end sockets are installed at the two ends of the straight barrel section of the winding core mold through cylindrical surfaces, and a plurality of layers of axial yarn and annular yarn are sequentially and alternately wound on the outer sides of the connecting rings or the metal end sockets and the straight barrel section of the winding core mold. Compared with operation of a traditional fiber winding machine, the axial yarn does not need to be cut off many times in the laying and winding process, a false end socket is not needed either, and the connection strength between the composite material and the connecting ring or the metal end socket is high; the production efficiency is improved by dozens of times by using the tubular laying and winding machine; manual operation is reduced, and the product quality is stable.

Description

Technical Field

[0001] The invention belongs to the technical field of solid rocket engines, and in particular relates to a connection structure and method between a metal connecting ring or a head of a large-opening engine and a composite shell. Background Art

[0002] The head section of the traditional medium and large composite solid rocket engine combustion chamber is made by winding, and the longitudinal fibers are reversely wound at the pole holes at both ends. Since the continuous fiber reinforced composite material has super strong bearing capacity only in the fiber direction, the special shape of the head is difficult to be wound in the circumferential direction, which makes the strength of this part in the circumferential direction low and must be reinforced with high-strength cloth. The increased mass of the reinforcement and the increased thickness of the longitudinal fibers due to the smaller winding radius objectively significantly reduce the advantage of composite materials over high-strength metal materials in this part. The mass of the composite head part is even greater than that of metal materials. What is more terrible is that the complexity of the composite head structure will significantly reduce the reliability during operation. The combustion chamber shell of a large-opening composite solid rocket engine generally adopts the carbon fiber and metal thorn winding connection technology to add one or two metal connecting rings at both ends of the composite material of the shell, and adopts a connection structure in which a false head is set outside the metal connector for winding. Before winding to the end, all the excess process yarns wrapped on the false head need to be cut off. Since the fiber winding machine can only wind several fiber bundles back and forth multiple times to lay out a complete fiber laying surface, not only is the efficiency low, but also because of the difficulty of reciprocating and reversing at the straight-through end, the connection between the fiber bundle and the metal connector mainly relies on the bonding force between the layers. Since the mechanical properties of the composite matrix resin are relatively low and the shear strength between the composite layers is also relatively low, the metal connector must use a longer bonding surface to withstand the huge axial force, thereby increasing the waste weight of the metal connector. Although CN115095448A proposes the use of a tubular laying and winding machine to circumferentially reinforce the composite head part and make an integrated composite skirt, due to the difference in performance characteristics between composite materials and metal materials, in many cases, the use of a metal head has better comprehensive performance than the use of a composite head. CN 112644039 A shows a combination of a composite cylinder and a metal head. The winding method at the joint is still the metal hanging wire ring connection technology that has been used in the composite industry 40 years ago. Since no new solutions have been proposed, its production efficiency is bound to be very low. Summary of the invention

[0003] The object of the present invention is to provide a structure and method for connecting a metal connecting ring or head of a large-opening engine with a composite shell to solve the above-mentioned problem.

[0004] To achieve the above object, the present invention adopts the following technical solutions: The connection structure between the composite shell of a large-opening combustion chamber and a metal connecting ring includes a connecting groove, a cylindrical surface, axial yarns and annular yarns. Several connecting grooves are arranged in a ring shape on the outer cylindrical surface of the metal connecting ring or the head. The innermost connecting groove on the metal connecting ring or the head is connected to the cylindrical surface. The metal connecting ring or the head is installed at both ends of the straight cylinder section of the winding mandrel through the cylindrical surface. Several layers of axial yarns and annular yarns are alternately wound on the outer sides of the metal connecting ring or the head and the straight cylinder section of the winding mandrel.

[0005] Furthermore, the connecting groove is an annular groove or a stepped groove; the winding pitch of the circumferential yarn is set according to the groove shape of the connecting groove so that the circumferential yarn in the groove portion becomes a flat tightening yarn.

[0006] Furthermore, when the connecting groove is an annular groove, the outer edge and the bottom edge of the connecting groove are both rounded.

[0007] Furthermore, when the connecting groove is a stepped groove, the yarn incoming side of the connecting groove is a conical surface.

[0008] Furthermore, the axial length of the cylindrical surface is not less than mm.

[0009] Furthermore, the metal head is transitionally combined with the composite material by using metal connectors.

[0010] Furthermore, a group of connection grooves are arranged on the outer circumferential surface of the metal connection piece at set intervals.

[0011] Furthermore, a thread is provided at the inner circle of the outer end of the metal connector for connecting to the nozzle or the metal head.

[0012] A method for connecting a metal connecting ring or a head of a large-opening engine to a composite shell includes the following steps: A set of connection grooves are made on the outer cylindrical surface of the metal connection ring or the head at a set interval, and then installed at both ends of the straight cylinder section of the winding core mold; A tubular laying and winding machine is used for laying and winding. Each time a layer of axial yarn is laid, a layer of circumferential yarn is wound on it. The axial yarn is laid and the circumferential yarn is wound back and forth until it meets the design requirements.

[0013] Furthermore, during fiber winding, each layer of axial yarn occupies a circle of connecting grooves of the metal connecting ring separately.

[0014] Compared with the prior art, the present invention has the following technical effects: The present invention uses a tubular laying and winding machine to make a group of connecting grooves at set intervals on the outer cylindrical surface of the metal connecting ring or the end cap, and then installs them at both ends of the straight section of the winding core mold; the tubular laying and winding machine is used for laying and winding, and each layer of axial yarn is wound on it with a layer of circumferential yarn, and the axial yarn is laid and the circumferential yarn is wound back and forth until it meets the design requirements. Compared with the operation of the traditional fiber winding machine, the axial yarn does not need to be cut off multiple times during the laying and winding process, and a false end cap is not required, and the connection strength between the composite material and the metal end cap is high; the production efficiency is increased by dozens of times by using the tubular laying and winding machine; the manual operation is reduced and the product quality is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The figure is a schematic diagram of a connection structure between a metal head and a composite shell according to the present invention.

[0016] Figure 2 The figure is a schematic diagram of a connection structure between a metal head and a composite shell according to the present invention.

[0017] Figure 3 The figure is a schematic diagram of a connection structure between a metal head and a composite shell according to the present invention.

[0018] Figure 4 The figure is a schematic diagram of a connection structure between a metal connection ring and a composite shell according to the present invention.

[0019] Among them: 1 - metal head, 2 - skirt, 3 - connecting groove, 4 - axial yarn, 5 - circumferential yarn, 7 - conical groove, 8 - tightening yarn, 9 - cylindrical surface, 10 - metal connecting ring, 11 - thread. DETAILED DESCRIPTION

[0020] The present invention is further described below in conjunction with the accompanying drawings: Example 1 See also Figure 1, a method for connecting a metal end cap with a skirt and a composite shell of a large opening solid rocket engine with an outer diameter of 90mm, firstly, a group of connecting grooves 3 are made on the outer cylindrical surface of the metal end cap, the innermost annular groove has a cylindrical surface 9 of 50mm in length from the innermost end surface of the metal connector, and the outer edge and bottom edge of the connecting groove 3 are both rounded. The metal end cap 1 is installed at both ends of the straight section of the winding core mold, and a tubular laying and winding machine is used for laying and winding. Each layer of axial yarn 4 is wound on it with a layer of circumferential yarn 5, and the winding pitch of the circumferential yarn is set according to the specific groove type of the connecting groove 3 so that the circumferential yarn in the groove portion becomes a flat tightening yarn, and the axial yarn is laid and wound repeatedly until the thickness meets the design requirements. Due to the long contact surface between the innermost axial yarn and the metal end cap 1 and the circumferential preload applied by the composite material cylinder during laying and winding, the composite material and the metal end cap can be closely combined and generate a sufficiently large pressing force and friction force, so that the composite material cylinder and the metal end cap will not separate when the rocket is working. In addition, the folding back of each layer of axial yarn in the head is completed in the annular groove 3, and the hoop yarn 8 wound in the annular direction is tightened into the annular groove 3. Under the conditions of space and weight permitting, the length of the thin-walled cylindrical surface 9 should be as long as possible to reduce the shear stress at the interface between the composite material and the metal head.

[0021] Example 2 See also Figure 2 , a method for connecting a metal head with a skirt and a composite shell of a large-opening solid rocket engine with a caliber of 122mm, firstly, a group of connecting grooves 3 are made on the outer circumferential surface of the metal head, the innermost annular groove is 60mm long from the innermost end surface of the metal connector, and the yarn side of the connecting groove 3 is a conical surface. The metal head 1 is installed at both ends of the straight barrel section of the winding core mold, and a tubular laying and winding machine is used for laying and winding. Each layer of axial yarn 4 is wound on it with a layer of circumferential yarn 5, and the winding pitch of the circumferential yarn is set according to the specific groove type of the connecting groove 3 so that the circumferential yarn in the groove becomes a special clamping yarn, and the axial yarn is laid and wound repeatedly until the thickness meets the design requirements. Due to the long contact surface between the innermost axial yarn and the metal head 1 and the circumferential preload applied by the composite material cylinder during laying and winding, the composite material and the metal head can be closely combined and generate a sufficiently large pressing force and friction force, so that the composite material cylinder and the metal head will not separate when the rocket is working. In addition, each layer of axial yarn 4 is folded back in the annular groove 3, and is tightened into the annular groove 3 by the annularly wound tightening yarn 8. Since the yarn-incoming side of the annular groove is a conical surface, the axial force borne by the axial yarn 4 can be better transmitted to the metal end cap 1.

[0022] Example 3 See also Figure 3A method for connecting a metal end cap with a skirt of a large-opening solid rocket engine with a diameter of 60 mm and a composite shell. First, a group of connecting grooves 3 are made on the outer circumferential surface of the metal end cap. The innermost annular groove is 35 mm away from the innermost end surface of the metal connector. The outer edge and bottom edge of the connecting groove 3 are both rounded. The metal end cap 1 is installed at both ends of the winding core mold straight tube section, and a tubular laying and winding machine is used for laying and winding. The current position and the model position of each longitudinal direction are both in the corresponding connecting groove 3. The axial yarn is pulled into the connecting groove 3 with a high modulus circumferential yarn and then turned back. After each longitudinal laying, a circumferential winding is performed. The axial yarn is laid and the circumferential yarn is wound back and forth until the thickness meets the design requirements. Due to the long contact surface between the innermost axial yarn and the metal end cap 1 and the circumferential preload applied by the composite material cylinder during laying and winding, the composite material and the metal end cap can be closely combined and generate a sufficiently large compression force and friction force, so that the composite material cylinder and the metal end cap will not separate when the rocket is working.

[0023] Example 4 See also Figure 4 A method for connecting a metal connecting ring 1 at both ends of a tubular combustion chamber of a solid rocket engine with a large opening of 70 mm in diameter to a composite shell. The metal connecting ring 10 is a tube-shaped body with a thread 11 and a group of connecting grooves 3. The innermost annular groove is a cylindrical surface 9 40 mm long from the inner end face of the metal connecting ring. The outer edge and bottom edge of the connecting groove 3 are both rounded. The metal connecting ring or end cap 1 is installed at both ends of the straight section of the winding core mold, and a tubular laying and winding machine is used for laying. The current position and the model position of each longitudinal direction are in the corresponding connecting groove 3. The axial yarn is squeezed into the connecting groove 3 with a high modulus circumferential yarn and then folded back. After laying two layers of axial yarn, a circumferential winding is performed. The axial yarn is laid and the circumferential yarn is wound repeatedly until the thickness meets the design requirements. Since there is a long contact surface between the innermost axial yarn and the small end of the metal connecting ring 1, and the circumferential preload applied by the composite material cylinder during winding, the composite material and the metal connecting ring can be tightly combined and generate sufficiently large compression and friction forces, so that the composite material cylinder and the metal connecting ring will not separate when the rocket is working. The connecting groove at the end of the axial yarn forms a reliable incarnation because the axial yarn can be squeezed into the circumferential yarn, so that the composite material can transfer more axial force to the metal connecting ring or the head to form a reliable connection.

[0024] Finally, it should be stated that the embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some or all of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A connection structure between a metal connecting ring or head of a large-opening engine and a composite shell, characterized in that: The invention comprises a connecting groove (3), a cylindrical surface (9), an axial yarn (4) and an annular yarn (5); a plurality of connecting grooves (3) are arranged in an annular shape on the outer circumferential surface of a connecting ring or a metal end cap; the innermost connecting groove (3) on the metal connecting ring or the end cap is connected to the cylindrical surface (9); the metal connecting ring or the end cap is mounted on both ends of a winding core mold straight tube section via the cylindrical surface (9); and a plurality of layers of axial yarn (4) and annular yarn (5) are alternately wound in sequence on the outer sides of the metal connecting ring or the end cap and the winding core mold straight tube section.

2. The connection structure of a metal connecting ring or head of a large-opening engine and a composite shell according to claim 1 is characterized in that: The connecting groove (3) is an annular groove or a stepped groove; the winding pitch of the circumferential yarn is set according to the groove shape of the connecting groove (3) so that the circumferential yarn in the groove portion becomes a flat tightening yarn.

3. The connection structure of a metal connecting ring or head of a large-opening engine and a composite shell according to claim 2 is characterized in that: When the connecting groove (3) is an annular groove, the outer edge and the bottom edge of the connecting groove (3) are both rounded.

4. The connection structure of a metal connecting ring or head of a large-opening engine and a composite shell according to claim 2, characterized in that: When the connecting groove (3) is a stepped groove, the yarn incoming side of the connecting groove (3) is a conical surface.

5. The connection structure of a metal connection ring or head of a large-opening engine and a composite shell according to claim 1, characterized in that: The axial length of the cylindrical surface (9) is not less than (15) mm.

6. The connection structure of a metal connecting ring or head of a large-opening engine and a composite shell according to claim 1, characterized in that: The metal end cap is transitionally connected to the composite material by using a metal connector (10).

7. The connection structure of a metal connection ring or head of a large-opening engine and a composite shell according to claim 6, characterized in that: A group of connection grooves (3) are arranged on the outer circumferential surface of the metal connection piece (10) at set intervals.

8. The connection structure of a metal connecting ring or head of a large-opening engine and a composite shell according to claim 6, characterized in that: A thread (11) is provided at the inner circle of the outer end of the metal connecting piece (10) for connecting to a nozzle or a metal end cap.

9. A method for connecting a metal connecting ring or head of a large-opening engine to a composite shell, characterized in that: The connection structure according to any one of claims 1 to 8 comprises the following steps: A group of connection grooves (3) are made on the outer circumferential surface of the metal connection ring or the end cap at set intervals, and then installed on both ends of the straight cylinder section of the winding core mold through metal connectors (10); A tubular laying and winding machine is used for laying and winding. Each time a layer of axial yarn is laid, a layer of circumferential yarn is wound on it. The axial yarn is laid and the circumferential yarn is wound back and forth until it meets the design requirements.

10. The method for connecting a large-opening engine metal head and a composite shell according to claim 9, characterized in that: When the fiber is laid, each layer of axial yarn occupies a circle of connecting grooves (3) of the metal connecting ring.

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